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This study seeks to understand the host factors that affect the replication and immune response of seasonal and candidate pandemic live attenuated influenza vaccine (LAIV) in humans and to develop biomarkers that can predict the viral shedding and immune response to LAIVs.

Influenza A viruses are widely distributed in nature and exist as many different subtypes. Pandemics of influenza can occur, and vaccine development is focused on those subtypes that are predicted to represent the greatest pandemic threat to the human population. This study seeks to understand the host factors that affect the replication and immune response of seasonal and candidate pandemic LAIVs in humans and to develop biomarkers that can predict the viral shedding and immune response to LAIVs.

Three vaccines will be evaluated: the licensed seasonal LAIV, with a focus on the H3N2 component; the H9N2 G9/AA ca vaccine, which is among the most immunogenic of the candidate pandemic LAIVs evaluated to date; and the H2N3 MO 2066/AA ca vaccine, which is among the least immunogenic of the candidate pandemic LAIVs evaluated to date. The seasonal LAIV will be evaluated in an outpatient setting, while the other two vaccines will be evaluated in an inpatient setting. In each setting, some participants will receive a placebo vaccine.

Study participants will be assigned to one of four groups. Participants who are seronegative to both H9N2 G9/AA ca and H2N3 MO 2006/AA ca viruses will be randomly assigned to receive one of those vaccines (Group 1: H9N2 G9/AA ca; Group 2: H2N3 MO 2006/AA ca) or placebo (Group 4) and will remain in an inpatient isolation facility. Participants who are seronegative to the H3 component of seasonal LAIV will be randomly assigned to receive either seasonal vaccine (Group 3) or placebo (Group 4) and will be followed as outpatients.

All participants will remain in the study for 56 days. Participants in the inpatient arms will be admitted on Day -2, will receive study vaccine on Day 0, and will undergo a basic history, physical examination, and nasal wash each day until discharge. On some study days, inpatient participants will undergo a blood collection and/or a nasal swab; at the screening visit and on Day -1 or Day -2, participants will give a urine sample.

Participants in the outpatient arms will receive study vaccine on Day 0 and will have study visits on Days 1, 2, 3, 4, 5, 6, 7, 14, 28, and 56. On Days 1 through 7, participants will undergo a basic history, physical examination, and nasal wash. On some visits, participants may undergo a blood collection and/or a nasal swab; at the screening visit and on Day -1, participants will give a urine sample. Unused blood or nasal wash samples will be stored and may be used in future research studies.

Exploratory Evaluation of Host Biomarkers That Predict the Vaccine Virus Replication and Immunogenicity of Seasonal and Pandemic Formulations of Live Attenuated Influenza A Virus Vaccines Based on the A/Ann Arbor/6/60 ca Master Donor Virus (MDV)

Area under the curve (AUC) of nasal virus shedding after vaccine dose as assessed by liquid titration of nasal secretions on Madin Darby Canine Kidney (MDCK) cells [ Time Frame: Measured through Day 9 ]

Development of serum antibody as assessed by either HAI or microneutralization (MN) assays [ Time Frame: Measured through Day 56 ]

Secondary Outcome Measures
:

Development of a significant increase in nasal secretion hemagglutinin (HA)-specific antibody assessed by enzyme-linked immunosorbent assay (ELISA) [ Time Frame: Measured through Day 56 ]

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Ages Eligible for Study:

18 Years to 42 Years (Adult)

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Yes

Criteria

Inclusion Criteria:

General good health, without significant medical illness, physical examination findings, or significant laboratory abnormalities as determined by the investigator

Agree to storage of blood specimens for future research

Available for the duration of the trial. For the inpatient component of the study, participants must be willing and able to remain within the Isolation Unit for the specified duration of confinement. For the outpatient component of the study, participants must be willing and able to make daily outpatient follow-up visits as specified by the protocol.

Willingness to participate in the study as evidenced by signing the informed consent document

Female participants must agree to use effective birth control methods for the duration of the study (for example, pharmacologic contraceptives including oral, parenteral, and transcutaneous delivery; condoms with spermicide; diaphragm with spermicide; intrauterine device; abstinence from heterosexual intercourse; or surgical sterilization). All female participants will be considered being of child-bearing potential except those who have undergone hysterectomy and those in whom menopause occurred at least 1 year prior to the study.

Exclusion Criteria:

Pregnancy as determined by a positive human choriogonadotropin (beta-HCG) test

Behavioral or cognitive impairment or psychiatric disease that in the opinion of the investigator affects the ability of the subject to understand and cooperate with the study protocol

Previous enrollment in an H2 or H9 influenza vaccine trial or in any study of an avian influenza vaccine

For the inpatient arm, seropositive to the H2N3 influenza A virus or the H9N2 influenza A virus (serum HAI titer >1:8). For the outpatient arm, seropositive to the H3N2 component of seasonal LAIV (serum hemagglutination inhibition [HAI] titer greater than 1:8).